Phonon dispersion curves and normal coordinate analysis of α‐poly‐<scp>L</scp>‐alanine

Abstract

Abstract The vibrational frequencies of α‐helical poly‐ L ‐alanine and its N ‐deuterated analog have been assigned by normal coordinate analyses. The phonon dispersion curves and frequency distribution of α‐poly‐ L ‐alanine have been calculated by using a model which includes hydrogen bonding. The frequency distribution was used to interpret the inelastic neutron scattering data and to calculate the heat capacity. The low‐frequency chain modes involving accordian‐like motions of the whole helix have been calculated and their dispersion investigated by means of a simplified model.